Overload release devices



Jan. 20, 1959 I J. A. HORN 2,869,453

Y OVERLOAD RELEASE DEVICES Filed Jan. 31, 1955 United States Patent 2,869,453 ov RLoAD RELEASE DEVICES James A. Horn, Lyons, 111., assignor to Western Electric Company, Incorporated, New York, N. Y., a corporation of New York Application January 31, 1955, Serial No. 485,252

3 Claims. (Cl. 100282) This invention relates to overload release devices for machines and more particularly to thrust members composed of low melting point alloys positioned in the actuating mechanisms of machines for relieving jams.

An object of this invention is to provide an improved thrust member for quickly relieving jams in machines such as presses without damage thereto.

Another object of this invention is to provide an improved thrust member in actuating mechanisms, which members may be melted by heat to relieve jamming pressures.

One embodiment of the invention for relieving jamming conditions in a press may include a ram for carrying a fabricating tool for forming stock, a connecting rod having one end secured in a socket in a bearing member positioned in a recess in the ram to actuate it, means for actuating the connecting rod, and a thrust member in the form of a disc of a low melting point alloy positioned between the bearing member and the bottom of the recess in the ram in alignment with a hole in the ram so that, when the tool is jammed in the stock, the ram may be heated until a portion of the disc reaches a fluid state and flows out through the hole in the ram to thus eliminate the jam in the press.

Other objects and advantages of the invention will become apparent by reference to the following detailed description thereof and the accompanying drawing illustrating a preferred embodiment of the invention, in which the disclosure is a diagrammatical front elevation of a press including one embodiment of the present invention, the ram of the press being sectioned to show its construction for retaining the low melting point disc thrust member.

Referring now in detail to the drawing, there is shown a press 11 having a frame 12 and a bed 13 on which stock 15 is positioned to be fabricated by a tool 16 carried by a ram 17 slidably mounted between guides 19 and 29, which are integral parts of the frame 12. The tool 16 is secured to the ram 17 by a clamp 41 of a wellknown type which is tightened by a bolt 43 to grip a shank 44 of the tool 16 between the clamp and the ram 17. A horizontal crankshaft 23 mounted in bearings 24 and 25 supported by the frame 12 is rotated by a motor 27 acting through gears 28 and 29 to operate a connecting rod 31 secured to the ram 17, thus raising and lowering the ram 17 between the guides 19 and 20. The connecting rod 31 passes through an adjustable locking ring 32 threaded into a vertical cylindrical recess 33 in the upper portion of the ram 17 and is secured to the ram 17 by a ball 35 secured to the lower end of the connecting rod 31 and held in a ball and socket relationship between the lower portion of the locking ring 32 and a cylindrical bearing member 34 having a socket 36 for the ball 35 and positioned below the locking ring 32 in the recess 33.

A thrust member in the form of a disc 37 of a low melting point alloy is positioned between the bearing 2,869,453 Patented Jan. 20, 1959 lCe member 34 and the bottom of the recess 33 in alignment with a horizontal bore 39 in the ram 17 so that, when the tool 16 becomes jammed in. the stock 15 at a point near bottom dead center, heat may be applied to the ram 17 in the region of the thrust disc 37 to melt a portion of the disc and allow it to flow out of the ram 17 through the bore 39 and thus relieve the jamming pressure to permit the crankshaft 23 to be rotated to raise the tool 16.

A plug 40 is threaded into the bore 39 to preveritpossible cold flow of the thrust disc 37 during normal operation of the press 11, the plug 40 being removed when it becomes necessary to melt a portion of the thrust disc 37 to relieve the jamming pressure.

The connecting rod 31 is provided with threaded parts 42 to permit adjustment of its length; it being necessary, after a portion of the thrust disc 37 has been melted and drained through the bore 39 to relieve the jam in the press 11, to adjust the length of the connecting rod 31 to compensate for the amount of the thrust disc 37 which has been removed by melting.

In operating the press to fabricate stock 15, the motor 27 drives the gears 28 and 29 to rotate the crankshaft 23, thus raising and lowering the ram 17 and the tool 16 between the guides 19 and 20 to do work on the stock. In the event the tool 16 jams in the stock 15 at a point near bottom dead center due to causes such as the accidental feeding of two pieces of stock 15 onto the bed 13 of the press 11, the plug 40 is removed from the ram 17 and the ram is heated in the region of the thrust disc 37 until a sufiicient amount of the disc 37 has melted and drained through the bore 39 to permit the crankshaft 23 to be turned past bottom dead center. This relieves the jamming pressure which otherwise might be sufllcient to break the frame 12. or some other part of the press 11 if the attempt was made to force the crankshaft 23 past bottom dead center.

After a portion of the disc 37 has been melted to relieve the jam, the plug 40 is replaced in the bore 39 and the amount of the thrust disc 37 removed by melting is compensated for by increasing the length of the connect ing rod 31 by adjustment of the threaded parts 42. The locking ring 32 is then threaded further into the recess 33 in the ram 17 to engage the ball 35 which has been moved downward by the increasing of the length of the connecting rod 31 to move the bearing member 34 into engagement with the remaining portion of the thrust disc 37.

After the thrust disc 37 has been completely melted and drained from the recess 33, one disc 37 being sufiicient for the relief of many jams since only a portion of the disc 37 is melted to relieve each jam, another thrust disc 37 may be inserted into the recess 33 by disassembling the connecting rod 31 and removing the locking ring 32 and the bearing member 34 from the recess 33 in the ram 17. When a new thrust disc 37 is inserted into the recess 33 the connecting rod 31 must be shortened by the adjustment of the joint 42 to provide the proper distance from the crankshaft 23 to the tool 16 and thus to the stock 15.

It is to be understood that the above-described arrangements are simply illustrative of the application of the principles of this invention. Numerous other arrangements may be readily devised by those skilled in the art it which will embody the principles of the invention and ram, a connecting rod driven by the actuating means and secured in the recess in the ram to transmit force from the connecting rod through the fusible thrust member to the ram, said ram having an aperture aligned with the fusible thrust member therein for permitting the thrust member to be melted and drained from the recess to relieve jamming pressure in the event that the tool be comes jammed in the stock, and means for plugging the aperture to prevent cold flow of the fusible member.

2. In an overload release device for a machine having a tool for fabricating stock, a connecting rod secured to and driven by the machine, a ram carrying the tool and having a recess therein, a fusible thrust member positioned in the recess in the ram, said connecting rod also being secured in the recess in the ram to transmit force 15 to the ram through the fusible member, said ram having an aperture aligned with the fusible member, and a removable plug secured in said aperture for confining the fusible thrust member to the recess during normal operation.

3. In an overload release device for a machine having a. stock fabricating tool, a connecting rod driven by the machine, a ram having a cylindrical recess intersected by a threaded aperture, a fusible thrust member positioned in the cylindrical recessin alignment with said aperture, means for securing the connecting rod in the cylindrical recess to transmit force through the fusible thrust member to the ram, and a plug threaded into said aperture to prevent cold flow of the fusible thrust mem- 10 her during normal operation.

References Cited in the file of this patent UNITED STATES PATENTS 1,847,620 Miller Mar. 1, 1932 FOREIGN PATENTS 565,839 Great Britain Nov. 30, 1944 

